Environmental inhibition of 11beta-hydroxysteroid dehydrogenase.

Gossypol, a polyphenolic compound from cotton seed, caused hypokalemia in some men receiving it in a trial of its contraceptive activity. Searching for the mechanism for its hypokalemic action led to the observation that it inhibited 11beta-hydroxysteroid dehydrogenase. This would enhance mineralocorticoid effect in the kidney. Many other polyphenols also inhibit this enzyme including those in grapefruit juice. Ingesting 1-2 l of grapefruit juice inhibited this enzyme in two men in a clinical experiment. Tea polyphenols inhibit this enzyme and add to the inhibition caused by gossypol. Men in China have lower serum potassium values than men elsewhere and this is due to the environment, presumably the diet, in China. The importance of dietary and other exogenous inhibitors of this enzyme in electrolyte metabolism remains to be determined.